The present invention relates to the process of manufacturing a semiconductor device. In particular, it relates to techniques of forming a metal film onto a to-be-processed body such as a semiconductor wafer.
In recent years, the demand for increased integration and miniaturization of semiconductor devices in semiconductor device manufacturing processes has become stronger, and in order to respond to those demands, there has been a considerable shift from using aluminum as the interconnect material or line material in film deposition processes to using copper or gold, which have lower resistance.
Currently with the metalorganic chemical vapor deposition (MOCVD) processes have been put into use, an organic metal that is liquid at room temperature and under normal pressure such as (hfac)Cu+1(tmvs) is vaporized and introduced into a process chamber, and a copper film is deposited while causing a pyrolytic decomposition reaction to occur on the wafer that is being held inside the process chamber.
Processes that are also given consideration involve applying the organic metal as it is or mixed with an organic solvent (an organometallic fluid) onto the wafer while heating the wafer that has been placed in the process chamber, and then causing a pyrolytic decomposition reaction to occur in order to form the metallic film.
Incidentally, when forming a metallic film such as copper, since there is a possibility that some atoms of the metal may disperse to the under layer, a barrier metal layer such as tantalum or tantalum nitride has conventionally been formed before depositing the metal film.
However, even if this type of barrier metal layer has been formed, problems tend to develop such as either the ohmic value of the metal film showing a value that is higher than the desired value, or the adhesion of the metal film being low.
The object of the present invention is to provide a method of film deposition, and an apparatus thereof, that can perform film deposition of a metallic film without having the problems described above.
In order to reach this objective, the inventors considered many variables. As a result, they concluded that the barrier metal layer might be affected by factors such as natural evaporation since the wafer is conventionally exposed to air after the barrier metal layer is formed.
Accordingly, the present invention is a film deposition method that forms a metal layer after forming a barrier metal layer on a to-be-processed body; wherein one series of processing from formation of the barrier metal up to and including formation of the metal layer is performed in an environment cut off from air.
More specifically, the performing of the barrier metal layer formation in a first device and the metal layer formation in a second device; and the transport of a to-be-processed body from the first device to the second device is performed through a transport pathway that is cut off from air.
In addition, it is preferable that the metal layer formation comprise a first step of preparing an organometallic fluid, which contains an organic metal such as (hfac)Cu+1(tmvs) as its main component and which precipitates a metal layer material through a pyrolytic decomposition reaction, and then applying the organometallic fluid onto the to-be-processed body at a temperature within the non-reactive range of the organic metal; and a second step of heating the to-be-processed body to a predetermined temperature after the first step, and causing a pyrolytic decomposition reaction of the organic metal within the fluid that is applied to the to-be-processed body. In this manner, by performing application and heating separately, it is possible to apply a film having even layer thickness and quality; and in addition since it is possible to cause a pyrolytic decomposition reaction to occur throughout the surface, a metal layer may be obtained having superb layer thickness and quality throughout its surface.
Moreover, it is preferable that, after formation of barrier metal layer, a thin film of the same metal material as that of the metal layer be formed on the barrier metal layer as a seed layer.
The film deposition apparatus that embodies the film deposition method of the present invention is most effective when it comprises a first device, which forms a barrier metal layer in an environment that is cut off from air; a second device, which forms a metal layer in an environment that is cut off from air; and a transport pathway, which connects the first device and the second device, and is cut off from air.
It is preferred that this film deposition apparatus further comprise a third device that forms a thin layer made of the same metal material as that of the metal layer, as a seed layer in an environment cut off from air.
The above and other features and advantages of the present invention will become more apparent from the following detailed description to those skilled in the art, when taken in conjunction with the accompanying drawings.